Generally, polycarbonate resins are excellent in impact resistance, and improvement of them by blending with other resins have been widely attempted. For example, crystalline resins such as polyester and polyamide are added to improve the solvent resistance of a polycarbonate resin. However, mere addition of crystalline resin had a problem in lowering impact resistance, although solvent resistance is improved. To overcome the above problem, a composition obtained by blending polyalkylene terephthalate and polycarbonate-polysiloxane copolymer are blended with polycarbonate (Japanese Patent Application Laid-Open No. 215652/1986), a composition comprising polycarbonate-polysiloxane copolymer and polyamide (Japanese Patent Application Laid-Open No. 213557/1988) and so on have been proposed. Both the polycarbonate resin compositions, however, had a problem in that they were poor in heat resistance, although improved in impact resistance.
Further, attempts have been proposed to improve polycarbonate resins in low-temperature impact property by adding a thermoplastic amorphous resin such as acrylonitrile-butadiene-styrene (ABS), and styrene-maleic anhydride copolymer (SMA). By mere addition of thermoplastic amorphous resin, however, the impact resistance of the resulting polycarbonate resin was insufficient. In order to overcome the above problem, a polycarbonate resin comprising polycarbonate-polysiloxane copolymer, acrylonitrile-butadiene-styrene (ABS) and acrylonitrile-styrene (Japanese Patent Application No. 287956/1986), and a polycarbonate resin comprising polycarbonate-polysiloxane copolymer, and styrene-maleic anhydride copolymer (SAM) (Japanese Patent Application Laid-Open No. 146952/1987) have been proposed. Both of these polycarbonate resin compositions, however, had a problem in that they are poor in Izod impact resistance.
Moreover, attempts to improve the sliding characteristics of polycarbonate resin by adding fluorine resin, for instance, have been made. Polycarbonate resin compositions which resulted from these attempts are, for example, a polycarbonate resin comprising polycarbonate-polysiloxane copolymer, styrene-maleic anhydride copolymer (SMA), phosphide and polytetrafluoroethylene (Japanese Patent Application No. 277464/1987), and a polycarbonate comprising polycarbonate-polysiloxane copolymer, SMA and the like, phosphide, Teflon and acrylonitrile-butadiene-styrene (ABS) (Japanese Patent Application No. 285948/1987). In these polycarbonate resin compositions, however, although impact resistance was improved by the use of polycarbonate-polysiloxane, the effect of the improvement was not sufficient.
Furthermore, attempts have been made to improve the impact resistance of polycarbonate resin by adding a rubber-like elastomer. However, by mere addition of a rubber-like elastomer, improvement in impact resistance could not be expected in a range where strength and elasticity of a polycarbonate resin were not largely lowered. Polycarbonate resins which are improved in the above problem are a polycarbonate resin comprising polycarbonate-polysiloxane and acrylic rubber or graft copolymer to polydimethyl siloxane (PDMS), and rubber (Japanese Patent Application No. 200161/1986) and a polycarbonate resin comprising polycarbonate-polycyloxane and isobutylene (Japanese Patent Application No. 51452/1988). In these polycarbonate resin compositions, however, impact resistance is improved since polycarbonate-polysiloxane was used, but the effect in the improvement was small.